First, the AI shouldn't be looking for sneaked players just because they've sneaked. It should go around looking for sneaked players where there aren't any visible players. It doesn't make sense going on a potential wild goose chase for the guy who disappeared when you have a threat within sight to deal with.
However, if there aren't any threats in sight, the best procedure for finding a sneak is as simple as walking in a small circle. In other words, enemies just check their back (and sides) real quick to make sure there's no one about to get the drop on them from behind.
After that, I imagine most enemies would return to their previous location (or patrol route). Maybe heal up first. Perhaps a few of the more adventurous enemies would actually try to hunt the invisible party members down. Point being, it should be some kind of behavior (not standing still), and it should vary from encounter to encounter.
Last edited by ScrotieMcB; 26/07/14 10:49 AM.